Read&Write for Google Chrome is able to insert voice notes into Google Slides
To do this, open your Read&Write for Google Chrome toolbar in a Slide and click the Voice Notes feature on your toolbar. This will open the recording window where you can record and listen back to your voice note. Once you are ready, you can click the "comment" button to insert into the Slide.
Important Note: Previously users were able to manually insert voice notes recorded with Read&Write for Google Chrome in Docs from their Google Dive "My Voice Notes" folder. We have moved to .ogg audio files for voice notes which will not allow this manual insertion from Drive in Slides.
The workflow should be to record and insert your voice notes with the Read&Write toolbar inside your Slides